A Moscow court on Tuesday began hearing the defamation lawsuit filed by Russian billionaire Alisher Usmanov against Alexei Navalny. Usmanov is demanding that the opposition leader refute the bribery allegations against him raised in Navalny's documentary about the secret wealth of Russian Prime Minister Dmitry Medvedev.

The documentary, released by Navalny's Anti-corruption Foundation in early March, claimed that Usmanov had transferred a luxury mansion at a high-end location in the Moscow region to a charity foundation run by Medvedev's university classmate. The politician also published legal documents showing that the deal had taken place. "We understand perfectly well what this kind of gift means: It's a bribe," said Navalny.

Usmanov claimed that Navalny had deliberately spread information that "contradicted reality." Usmanov also demanded that a number of Navalny's other allegations against him be refuted as well. In his earlier publications, the opposition leader among other things accused Usmanov, who owns assets in industries like mining and media, of seizing Soviet mining and processing plants, tax evasion and failing to create jobs. Navalny also claimed that Usmanov had bribed First Deputy Prime Minister Igor Shuvalov.

Navalny tried to summon Medvedev as a witness

Usmanov didn't show up in the court room during the seven-hour trial on Tuesday, having sent his lawyer Genrikh Padva to participate in the process on his behalf. Navalny, who was wearing a suit, arrived at the court personally. At the beginning of the hearing his lawyer Ivan Zhdanov filed motions to summon Medvedev and Shuvalov to testify at the proceedings. According to Zhdanov, only the prime minister and his deputy personally can give the clarification of their alleged connection to Usmanov.

The process doesn't make sense without granting the motion to summon Medvedev, Navalny said in the court room. "Usmanov is protecting not only his own interests in this process and primarily not his interests," he added. The court, however, dismissed both motions.

An unidentified federal official told the RBC website earlier this month that the billionaire had coordinated his lawsuit against the politician with the Kremlin. Usmanov filed his lawsuit on April 12, a month after the documentary was released. The film triggered a wave of mass street protests in dozens of Russian cities in late March, which were organized by Navalny.

The whistleblower and video blogger, who plans to run for president next year, also called on his supporters to hold protest rallies against corruption on June 12, the Russia Day public holiday. Earlier this month, Navalny had to undergo eye surgery in Spain after an antiseptic liquid, "brilliant green," was splashed on his face in Moscow. Navalny accused the Kremlin of organizing the attack and an earlier incident with "brilliant green," which has recently become a new weapon used against government critics in Russia.

Battle taken online

After the court hearing on Tuesday, Navalny told reporters that Usmanov "will not manage to distract attention from Medvedev." In the meantime the two opponents also took their battle online, having released videos in which they attack one another.

In a 12-minute video posted to YouTube, Usmanov addresses Navalny as "Lyosha," the short form of his name, in a quiet and condescending tone. He accuses Navalny of lying, and calls him "loser" and "failed businessman." Usmanov also demanded that Navalny apologize for the allegations against him. "You will have to answer to me for this anyway, Lyosha," he said. "You should have apologized and lived in peace because someone like you would never ever be able to prove that I'm a criminal, that I'm a thief," Usmanov added. The video ends on an unexpected note: "I spit on you, Alexei Navalny," the businessman said.

The opposition leader refused to apologize. He claimed that Usmanov's video had been recorded at the Kremlin's order and is aimed at deflecting attention away from the authorities and their illegal actions. Navalny also released a video of his own in which he proposed Usmanov join him for a one-on-one televised debate. In response to that request, the billionaire recorded another video last week saying that he "had expected apologies and not a debate."

"We will have debate in the court now," said Usmanov. "The difference between truth and lie will be explained to you there." Usmanov finished his address with the same phrase that went viral online after his earlier video: "I spit on you again."

The hearing of Usmanov's lawsuit will continue on Wednesday, with both parties presenting their arguments.